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TREATMENT IN  CASES   OF  POISONING                                   451

2. Use of Antidotes.—Antidotes are remedies which counteract the
effects of poisons. They are divided into mechanical, chemical, and physio-

Mechanical antidotes are those which render poisons inert "by mechanical
action. For instance, finely powdered charcoal acts mechanically by
absorbing and retaining within its pores organic and also, to a less degree,
mineral poisons. Fats, oils and egg albumen prevent the action of the
poison by forming a coating on the mucous membrane of the stomach.
Bulky food acts as a mechanical antidote to glass, as it prevents its action by
imprisoning its particles within its meshes.

Chemical antidotes are those which counteract the actions of poisons by
forming harmless or insoluble compounds when brought into contact with
them.   The examples are acids for alkalies, alkaline carbonates and taag-j
nesia for mineral acids, lime for oxalic acid, sodium sulphate for lead and?
tannin and albumin for alkaloids.    It must be remembered that only those j
substances should be selected as chemical antidotes which are by themselves1
almost harmless, so that if an excess is given they will not produce any ill-
effects.   Thus, vinegar or lemon-juice should be used as an antidote to a
caustic alkali, but not a mineral acid, such as hydrochloric or sulphuric acid
which, if given in excess, might prove as harmful as the original poison.

From his experiments on animals Jona has proved that the administra-
tion of adrenaline delays the absorption of rapidly acting poisons, such as
cyanides, strychnine and aconite, by its constricting action on the vessels of
the gastric mucosa.17

A very important chemical antidote is potassium permanganate owing to
its oxidizing properties. A solution of potassium permanganate in the pro-
portion of 10 to 15 grains in the pint is commonly used in opium poisoning,*
but should be used in poisoning by oxidizable substances, such as phospho-J
rus, hydrocyanic acid, cynides, barbituric acid and its derivatives, morphine/
atropine and other alkaloids. The patient should drink as much as he can
of it both beforfe and after vomiting or it should be introduced by means of
the stomach tube when the patient is unconscious. If this remedy is used,
the magistrate should be informed of the fact as its use greatly decreases
the chance of detection by the Chemical Examiner. This, however, should
not deter the medical man from using the drug, as his duty is to save life.
If in doing so he destroys evidence that might be useful to the police, that
is sad for the police, but is no concern, of the doctor. If without harming
the patient he can obtain material -eŁ~widential value, then by all means &e
should do so but not otherwise. Hence, before trying the permanganate, lie
may wash out the stomach with water and preserve this washing for the
Chemical Examiner, if it is possible to do so without causing the patient to,
undergo any extra risk.                                               '            ,

If potassium permanganate is not available, a solution of tincture iodine
in a dose of 15 drops to half a glass of warm water may be used to wasit 0u4
the stomach, as it precipitates iwst alkaloids.                                    ,; V-»

The following formula is a useful chemical aMt<fete which is recom-
mended in cases where the nature of tl^e poison swafflf^y-ed is not ctefinitely
known, or in cases where it is,suspected that a combination of two or more
poisonous Substances had been taken:—•/

Powdered charcoal
Tannic acid